DESCRIPTION (provided by principal investigator): Mobility problems affect 1/4 of all Americans aged 70 years or older. Primary care--based mobility testing has been advocated as an important clinical test for identifying those at risk for subsequent mobility decline and disability. Ideally, rehabilitation for those at risk should address the impairments that are most responsible for mobility decline. We define these as Rehabilitative Impairments and have identified 9 rehabilitative impairments as encompassing the most common foci of contemporary rehabilitation programs. In recognizing that many of these factors are interrelated, our previous work and experience suggests that rehabilitative impairments are encompassed within four distinct categories (Strength, Speed, Stability and Capacity), which we refer to as Rehabilitative Impairment Domains (RID). We hypothesize that the final common pathway between the most common medical conditions and mobility decline will be characterized by differing patterns of RID presentation. Surprisingly, given the high prevalence of mobility limitations and their clinical importance, there are no established mobility care guidelines concerning mobility risk factor screening and intervention as a means of preventing disability among older primary care patients. For older patients vulnerable to fatigue and frailty, optimal mobility rehabilitation should be directed toward those few RID and RID combinations most responsible for mobility decline. However, without better evidence determining which impairments and nonphysical factors to prioritize through rehabilitation, rehabilitative care will inevitably be more an art than a science - dependent on the subjective views and experiences of individual practitioners. In contrast, with a clearer understanding of the risk factors to target, rehabilitative care can be a vital component of a successful primary-care based disability prevention strategy. We propose to conduct a prospective cohort study among 420 primary care patients, aged 65 years and older that manifest preclinical disability. Over 2 years of follow up, we plan to evaluate these 9 rehabilitative impairments identifying the distinct RID patterns most responsible for decline and disability. Preliminary work suggests that RID characteristic of Strength, Speed, Stability and Capacity may be most responsible. This investigation will address three specific aims: (1) At baseline, we will examine the RID represented by these 9 rehabilitative impairments and evaluate what patterns of RID are associated with current mobility limitation as measured by the Function component of the Late Life Function and Disability Instrument (LLFDI); (2) We will test which RID and RID combinations presenting at baseline predict future decline in mobility function as measured by the Function component of the LLFDI over two years; (3) We will test which RID and RID combinations present at baseline predict the progression of disability as measured by the Disability components of the LLFDI over two years. Filling this knowledge gap will allow for the development of primary care-based rehabilitative strategies to prevent disability.